karla bennett may 2012. kingdom: animalia phylum: arthropoda class: insecta order: diptera ...
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Cochliomyia hominivorax
Karla Bennett May 2012
Taxonomy
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Diptera Family: Calliphoridae Genus: Cochliomyia Species: Cochliomyia hominivorax
Brief Information
It is called the “New World Screw-Worm Fly” It is a parasitic fly whose larvae (maggots)
feed on living tissue of warm-blooded animals. (Yes, it is a man-eating fly).
The infestation of a live vertebrate is called “myiasis”
There are 5 species of Cochliomyia but only 1 species of screw worm fly.
They are unusual because they prefer healthy tissues and not putrid tissues.
MMM! FLESH!
Distribution Range: Central and southern U.S. through mexico, Central
America, Carribean Islands, and Northern South America. U.S. and Mexico are using “sterile insect techniques”.
Now the disease border is between Mexico, Guatemala, and Belize.
The red color on the map shows the New World distribution.
Life Cycle
Life cycle overview
Definitive Host= Humans or any warm-blooded animal Intermediate Host= None Fly lays its eggs in a wound 24 hours later larvae emerge and feed and burrow
their heads into the tissue. Odor of wound attracts adult female to lay more eggs
(3000 larvae/wound 5-7 days larvae mature and drop to the ground,
burrow, and become “pupates”. Adults (8-10mm) emerge in the morning in 1-3 days. They mate within 1-3 days. Females then seek out a host to lay her eggs on (laid
in a shingle-like batch).
Symptoms
Motion inside a wound A wound becoming worse Serosanguineous discharge and odor from
the wound. Larvae can be seen in the wound after 3
days (vertical orientation in the wound) They burrow deeper if disturbed Animals with it (specifically grazing animals)
will lie down in the shade and show decrease in appetite and if milk producing will have decreased production.
Diagnosis
Identification of parasite under the microscope (can see distinctive larvae and eggs are laid in a particular pattern)
Cuticular hydrocarbon analysis Analysis of mitochondrial DNA and random amplified
DNA polymerase chain reaction (RAPD-PCR) assays. Larvae resemble a wood screw with a pointed head
and blunt back end. They have brown spines that encircle the body.
Eggs are laid in a shingle-like array near the edge of the wound.
Treatment
Wounds can be surgically excised The best treatment is the use of
larvacide. The treatment is repeated until the wound heals
Larvae must be destroyed otherwise they can leave and become adults.
Control
Reduced and then eradicated by repeatedly releasing sterilized male flies so that the flies mate and only produce unfertilized eggs.
Mini Quiz!
What phylum? What is the common name of the parasitic fly? Who is the intermediate host? How did the U.S. eradicate this fly? What stage is the fly in when it burrows into
the ground? Why shouldn’t you itch the wound being
affected by the larvae? Why are these flies so unusual as compared
with other flies? (hint: has to do with where they lay their eggs).
Citations
http://www.fao.org/ag/aga/agap/frg/feedback/war/u4220b/u4220b07.htm#geographical%20distribution%20of%20new%20and%20old%20world%20screwworm%20flies
www.cfsph.iastate.edu/Factsheets/pdfs/screwworm_myiasis.pdf
Wikipedia (for picture only) http://en.wikipedia.org/wiki/Cochliomyia
http://www.naiaonline.org/guest_editorials_and_commentary/page/suffering-to-end-suffering-the-heroic-effort-to-eradicate-the-north-america
http://www.kmle.co.kr/search.php?Search=Cochliomyia+hominivorax&SpecialSearch=HTMLWebHtdig&Page=3
http://www.sciencephoto.com/media/146978/enlarge
http://www.impactlab.net/2008/05/08/frightening-new-face-of-evil-the-screw-worm/